The present invention relates to a method of preparing densified wood impregnated with phenolic resin. More particularly, it relates to an improved method of preparing densified wood having a high phenolic resin content and a high mechanical strength by impregnating and reinforcing the wood with a phenolic resin solution obtained by blending about 0.6 to about 4 parts by weight of methanol, acetone, or a mixture of methanol and acetone per part by weight of the solid content of a resole-type phenolic resin under a high pressure of about 10-50 Kgs/cm.sup.2.
Densified wood impregnated with phenolic resins is known and is used for electric insulation boards, handles of knives, door knobs, etc. However, since the phenolic resins used for these purposes generally do not easily permeate into wood tissues, densified wood has been manufactured by slicing wood into veneers of 1-2 mm in thickness and putting the veneers into the impregnation tank of an impregnator, and after evacuating the air of the tank, feeding the phenolic resin into the tank and impregnating the veneers with the phenolic resin from the sliced faces under vacuum, or further impregnating the veneers with the phenolic resin for a short time under a pressure of 0-5 Kgs/cm.sup.2, then taking out the impregnated veneers from the tank and removing the excessive resin on the surfaces of the veneers, pre-drying the veneers at a temperature of 80.degree.-100.degree. C, and after piling up the veneers in 10-50 layers, hot-pressing the veneers at a temperature of 130.degree.-200.degree. C under a pressure of 20-100 Kgs/cm.sup.2 for 20-100 minutes, and followed by finishing.
The aforementioned conventional method for manufacturing such densified wood, is defective in that the yield of the densified wood product from the raw timber is low because of the necessity to slice the wood into veneers before impregnation. Wood resources are now gradually decreasing, and especially the domestic broadleaved tree resources such as birch, beech, maple, etc. which have dense textures and beautiful grains, and which are most suitable as raw materials for phenolic resin-impregnated densified wood preparation are being exhausted markedly. Accordingly, increasing the yield of the densified wood product from the raw timber is highly desirable. To achieve this purpose, it is desirable that blocks of raw timber be impregnated with phenolic resins without previous slicing of the wood into veneer. However with the conventional impregnating techniques mentioned above, phenolic resin cannot penetrate deeply into the unsliced wood blocks.